1. Field of the Invention The present invention relates to an electron-beam exposure apparatus and, in particular, to a variable shaping type electron-beam exposure apparatus which is capable of a blanket exposure used in the production of semiconductor devices or the like.
2. Description of the Related Art
FIG. 3 shows a schematic construction of a conventional variable shaping type electron-beam exposure apparatus. This exposure apparatus was presented at the 50th Applied Physical Society science lecture meeting. After an electron beam 5; emitted from an electron gun 1, is formed into a rectangular beam in cross section after passing through a first aperture member 2, it is deflected by a beam-shaping deflector 3 and is made to strike a desired block pattern of a second aperture member 4. Further, the electron beam 5 which has passed through the second aperture member 4 is projected on a desired position of a sample 9 placed on an X-Y stage 10 by means of a beam position deflector 8, causing the block pattern to be exposed to light. Numerals 6 and 7 denote electromagnetic lenses for causing the electron beam 5 to converge.
The first aperture member 2 has one rectangular pattern 2a in the center, as shown in FIG. 4. Meanwhile, in the second aperture member 4 are formed a plurality of block patterns 4a to 4e consisting of one or more figures, as shown in FIG. 5.
When the exposure of one block pattern out of the block patterns of the second aperture member 4 in the above way is terminated, this time the electron beam 5 is deflected by the beam shaping deflector 3 and is made to strike the next block pattern. Further, the electron beam 5 which has passed through this block pattern is projected in the desired position on the sample 9 by means of the beam position deflector 8.
The beam position deflector 8 can usually deflect the electron beam 5 only in an area of approximately 2 mm square on the surface of the sample 9. Therefore, by moving the X-Y stage 10, exposure can be performed over the entire surface of the sample 9.
However, in exposing a block pattern formed on the peripheral edge of the second aperture member 4, the electron beam 5 must be deflected greatly by the beam shaping deflector 3, as shown in FIG. 3. If the electron beam 5 is deflected greatly in this manner, since the electron beam 5 passes through the peripheral edge of the electromagnetic lens 7, a problem will arise in that various aberrations will occur and pattern exposure with a high degree of accuracy is difficult to effect.
Also, if an attempt is made to suppress aberration caused by the electromagnetic lens 7, it is necessary to diminish the amount of the deflection of the electron beam 5. As a result, a problem will arise in that the number of block patterns which can be formed in the second aperture 4 is limited.